用户名: 密码: 验证码:
SiO_(2f)/SiO_2-BN复合材料的尿素法制备工艺及性能研究
详细信息    本馆镜像全文|  推荐本文 |  |   获取CNKI官网全文
摘要
SiO_(2f)/SiO_2复合材料是高温透波领域应用较为广泛的一种导弹天线罩材料,但其力学性能相对较差,且烧蚀特性和高温透波不理想,使其应用范围受到限制。而PIP法制备的SiO_(2f)/Nitride复合材料虽然具有较高的力学性能、较好的烧蚀特性和高温透波性能,但是先驱体合成的工艺较危险,且成本较高。因此,本实验采用尿素法结合溶胶-凝胶工艺制备SiO_(2f)/SiO_2-BN复合材料,以期改善SiO_(2f)/SiO_2材料的不足和制备SiO_(2f)/Nitride复合材料PIP工艺的不足。
     本文首先从热力学的角度,研究了以尿素和硼酸为原料、采用尿素法合成BN的热力学过程。热力学计算分析表明,尿素法合成BN为吸热反应,当温度高于888K时反应可正向自发进行,且温度越高,氮化反应进行的越彻底;另外,提高反应物料中尿素的含量,可明显增加BN的平衡产率。计算结果也表明,当硼酸和尿素的配比为2:4,反应温度为850℃时,BN的平衡产率为88.09%。
     本文对尿素法的反应机理进行了初步探讨。研究结果表明,尿素法反应过程中,硼酸和尿素于100℃至350℃发生分解,分解的氨气和氧化硼于780℃左右反应生成BN,至800℃,氮化反应基本结束。
     本文研究了配料比及水和乙醇做为溶剂对尿素法合成BN纯度的影响规律。研究结果表明:在有溶剂和无溶剂条件下,硼酸和尿素的理想摩尔比均为2:4,此时反应产物中BN具有较高的纯度。
     本文基于对尿素法合成BN的反应热力学过程和反应机理的分析及实验结果,研究了原始SiO_(2f)/SiO_2复合材料密度、溶剂及工艺参数等因素对SiO_(2f)/SiO_2-BN复合材料组成、结构及性能的影响规律。研究结果表明:(1)原始材料SiO_(2f)/SiO_2材料的密度越大,所获得SiO_(2f)/SiO_2-BN复合材料的力学性能就越高,但是对密度和孔隙率的影响却非常有限;(2)乙醇溶剂为相对理想的选择,可以有效地改善SiO_(2f)/SiO_2-BN复合材料的力学性能;(3)尿素法工艺理想的制备温度为850℃,同时随着尿素法工艺次数的增加,SiO_(2f)/SiO_2-BN复合材料的密度逐渐增加,弯曲强度不断提高,当尿素法工艺循环四次时SiO_(2f)/SiO_2-BN复合材料获得最优的力学性能,此时复合材料的密度达到1.797g·cm~(-3),BN的质量分数为7.87%,弯曲强度更是达到了56.24MPa,比相应原始材料SiO_(2f)/SiO_2复合材料弯曲强度提高了108.29%。
     实验结果还表明,实验制备的SiO_(2f)/SiO_2-BN复合材料相较原始SiO_(2f)/SiO_2复合材料相比,力学性能有明显改善,同时具有良好的介电性能和热物理性能。其介电常数和介电损耗分别可低至3.12和0.005;室温至1000℃范围内的热膨胀系数小于0.5×10~(-6)/℃;导热系数约为1.07W/m·K。
SiO_(2f)/SiO_2 composites are widely used as a missile radome material in the field of high temperature wavetranspanrent, but its mechanical properties are relatively poor, and the characteristics of ablation and high temperature wavetransparent are not ideal, so its application scope is limited in a certain extent. Although SiO_(2f)/nitride composites what are made by PIP craft have higher mechanical properties, and the characteristics of ablation and high temperature wavetransparent are better, but the synthesis process of precursor is dangerous, and the cost is higher. Therefore, this experiment prepared SiO_(2f)/SiO_2-BN composites by urea route and sol-gel craft, so as to improve the deficiencies of SiO_(2f)/SiO_2 composites and SiO_(2f)/nitrides composites.
     In this paper, taken the urea and boric acid as raw materials, the thermodynamics process of BN synthesized by urea route was studied from the thermodynamics angle. Thermodynamic calculations show that, the reaction of BN synthesized by urea route is endothermic reaction; the reaction can be carried forward spontaneously when the temperature is higher than 888K; and the higher the temperature, the more complete the nitridation reaction. In addition, to improve the urea content of reaction materials, the balance yield of BN can be increased obviously. The experimental results also show that, when the ratio of boric acid and urea is 2:4, the balance yield of BN is 88.09% at 850℃.
     In this paper, the reaction mechanism of urea route was discussed firstly. The results show that, in the reaction process of urea route, boric acid and urea are decomposed at 100℃to 350℃, the BN is synthesized about 780℃by decompositions of ammonia and boron oxide, the nitride reaction basically endes at 800℃.
     In this paper, the influence laws that the ingredients ratio, water solvent and ethanol solvent effect on the purity of BN synthesized by urea route was studied. The results show that, in a solvent and solvent-free condition, the ideal molar ratio of the boric acid and urea is 2:4, right now BN has higher purity in the reaction products.
     Based on the reaction thermodynamics process of BN synthesized by urea route, the reaction mechanism and the experimental results, the influence laws that the original SiO_(2f)/SiO_2 composites density, solvent, technological parameters and other factors effect on the structures and properties of SiO_(2f)/SiO_2-BN composites were investigated in this article. The results show that: (1) The greater the density of original SiO_(2f)/SiO_2 composites, the higher the mechanical properties of SiO_(2f)/SiO_2-BN composites, but the impact of density and porosity is very limited; (2) Ethanol solvent is relatively ideal choice, it can effectively improve the mechanical properties of SiO_(2f)/SiO_2-BN composites; (3) The ideal preparation temperature of urea route is 850℃, at the same time, the more the cycles of urea route, the greater the density of SiO_(2f)/SiO_2-BN composites, and the stronger the bending strength. when the fourth time circulation of urea route, SiO_(2f)/SiO_2-BN composites have optimal mechanical properties, at this time the density of the composites can reach 1.797g·cm~(-3), the mass fraction of BN is 7.87%, and the flexural strength increases more 108.29% than original SiO_(2f)/SiO_2 composites, it reaches 56.24MPa.
     The results also show that, compared to the original SiO_(2f)/SiO_2 composites, SiO_(2f)/SiO_2-BN composites not only have higher mechanical properties, but also have better dielectric and thermal physical properties. The dielectric constant and dielectric loss are respectively low to 3.12 and 0.005; the thermal expansion coefficient is less than 0.5×10~(-6)/℃from 25℃to 1000℃; and thermal conductivity is about 1.07W/m·K.
引文
[1]程梅莎.烧蚀对天线罩材料透波性能影响的试验研究[D].北京:北京空气动力研究所,2001.
    [2] Air defense artillery reference handbook[M].Washington D C:Headquarters,Department of the Army,2000.
    [3] R.C.Johnson.Antenna engineering handbook[M].New York:McGraw-Hill,Inc,1984.
    [4] M.C.Gilreath,S.L.Castellow.High-temperature dielectric properties of candidate space-shuttle thermal-protection-system and antenna-window materials[J].NASA TN D-7523,1974.
    [5]李斌.氮化物陶瓷基耐烧蚀、透波复合材料及其天线罩的制备与性能研究[D].长沙:国防科技大学,2007.
    [6]张大海,黎义,高文,等.高温天线罩材料研究进展[J].宇航材料工艺,2001,(6):1-3.
    [7]彭望泽.防空导弹天线罩[J].北京:宇航工业出版社,1993.
    [8] C.G..Dodds,R.A.Tanzilli.Boron nitride-toughened single phase silicon aluminum oxynitride composite,article and method of making same[P].US Patent,5925584,1999.
    [9]王思青.石英-氮化物陶瓷基天线罩材料及构件的制备工艺与性能研究[D].长沙:国防科技大学,2006.
    [10] S.S.Oleesky,C.E.Peach,G..B.Speen,et al.Multiple sandwich broad band radome[P].US Patent,3002190,1961.
    [11] D.Lewis,J.R.Spann.Assessment of new radome materials as replacement for pyroceram 9606[A] . Proceedings of 16th symposium on electromagnetic windows[C],Georgia,1982.
    [12] H.Leggett.Ceramic broadband radome[P].US Patent,4358772,1982.
    [13] K.N.Letson,W.G..Burleson.Final evaluation of rain erosion sled test results at Mach 3.7 to 5.0 for slipcast fused silica radome structures.AD A077348,1979.
    [14] J.T.Neil,L.J.Bowen,B.E.Michaud.Fused silica radome[P].US Patent,4949095,1990.
    [15] T . M . Place , D . W . Bridges . Fused quartz reinforced silica composites[A] . Proceedings of the 10th Symposium on Electromagnetic Windows[C],Georgia,1970.
    [16] W.Ho,D.R.Clarke.High temperature millimeter wave dielectric propertiesof hot pressed silicon nitride[A] . Proceedings of 16th symposium on electromagnetic windows[C],Georgia,1982.
    [17] M.Y.Hsieh,H.Mizuhara.Silicon nitride having low dielectric constant[P].US Patent,4708943,1987.
    [18] M.Y.Hsieh.Low dielectric loss silicon nitride based material[P].US Patent,4654315,1987.
    [19] T.Arakawa,T.Mori,Y.Matsumoto.Silicon nitride sintered body and process for preparation thereof[P].US Patent,5017530,1991.
    [20] K.Miura,Y.Hattori,Y.Matsuo.Process for the production of silicon nitride sintered bodies[P].US Patent,4521358,1985.
    [21] D.R.Messier,P.Wong.Effect of processing conditions on microwave dielectric properties of reaction-sintered silicon nitride[A] . Proceedings of the 13th Symposium on Electromagnetic Windows[C],Georgia,1976.
    [22] F . H . Simpson , J . Verzemnieks . Controlled density silicon nitride material[A].Proceedings of 16~(th) symposium on electromagnetic windows[C],Georgia,1982.
    [23] J.Barta,M.Manela,R.Fisher.Preparation and properties of silicon nitride for radome applications[A].Proceedings of 16th symposium on electromagnetic windows[C],Georgia,1982.
    [24]邹强.天线罩用氮化硅陶瓷材料烧结工艺的研究[D].天津:天津大学,2004.
    [25]顾立德.氮化硼陶瓷[M].北京:中国建筑工业出版社,1982.
    [26]张雯,王红洁,金志浩.先驱体热解制备BN复合陶瓷材料研究进展[J].兵器材料科学与工程,2004,27 (5):58-63.
    [27] N.Ooi,V.Rajan,J.Gottlieb,et al.Structural properties of hexagonal boron nitride Modelling Simul[J].Mater.Sci.Eng,2006,14:515-535.
    [28]曾昭焕.氮化硼的高温介电性能[J].宇航材料工艺,1993,23 (2):17-21.
    [29] T . M . Place , D . W . Bridges . Fused quartz reinforced silica composites[A] . Proceedings of the 10th symposium on electromagnetic windows[C],Georgia,1970.
    [30] J.P.Brazel,R.Fenton.ADL-4D6:a silica/silca composite for hardened antenna windows[A] . Proceedings of the 13th symposium on electromagnetic windows[C],Georgia,1976.
    [31] J.S.Lyons,T.L.Starr.Strength and toughness of slip-cast fused-silica composites[J].J.Am.Ceram.Soc,1994,77(6):1673-1675.
    [32]于翘.材料工艺[M].北京:宇航出版社,1993.
    [33]张立中.三向石英复合材料的断裂韧度KC的测试与分析[J].宇航材料工艺,1996,(4):26-29.
    [34]贾光耀,陈虹,胡利明,等.三向石英复合材料的研制[J].硅酸盐通报,2002,1:3-6.
    [35]贾德昌,周玉,雷廷权.热压工艺对SiO_(2f)/SiO_2复合材料结构与力学性能的影响[J].宇航材料工艺,2001,1:29-31.
    [36] C.M.Xu,S.W.Wang,X.X.Huang,et al.Processing and properties of unidirectional SiO_(2f)/SiO_2 composites[J].Ceram.Int,2007,33 (4):669-673.
    [37] H.Chen,L.M.Zhang,G.Y.Jia,et al.The preparation and characterization of 3D-silica fiber reinforced silica composites[J].Key.Eng.Mater,2003,249:159-162.
    [38] H.Chen,L.M.Zhang,G.Y.Jia,et al.Flexural properties of 3D-SiO_2/SiO_2 composites[J].Key.Eng.Mater,2003,24:163-166.
    [39] V.A.Chase,R.L.Copeland.Development of a 1200°F radome[J].Interim Engineering Report 3.AD 429387,1963.
    [40]胡连成,于翘,刘连元,等.俄罗斯航天透波材料技术[R].航天出国考察技术报告,1994,1:136-142.
    [41]肖永栋,刘红影,方晓敏.新型无机烧蚀材料的性能及潜在用途[J].玻璃钢/复合材料,2002,3:46-47.
    [42]田焕芳.石英增强磷酸盐复合材料制备和组织结构及力学性能[D].哈尔滨:哈尔滨工业大学,2003.
    [43]周燕,郭卫红,罗进文,等.磷酸盐基复合材料的纤维涂膜与性能的研究[J].功能材料,2004,35 (s):2127-2135.
    [44] T.M.Place.Properties of BN-3DX,a 3-dimensional reinforced boron nitride composite[A] . Proceedings of the 13th symposium on electromagnetic windows[C],Georgia,1976.
    [45] T.M.Place.Low loss radar window for reentry vehicle[P].US Patent,4786548,1988.
    [46]郭景坤,黄校先,庄汉锐,等.氮化硼纤维补强氮化硅防热天线窗材料[R].中国国防科技报告,GF-HY 863433,1986.
    [47] G.J.Qi,C.R.Zhang,H.F.Hu,et al.Preparation of three-dimensional silica fiber reinforced silicon nitride composite using perhydropolysilazane as precursor[J].Mater.Lett,2005,59 (26):3256-3258.
    [48] G.J.Qi,C.R.Zhang,H.F.Hu,et al.Crystallization behavior of three-dimensional silica fiber reinforced silicon nitridecomposite[J].J.Cryst.Growth,2005,284 (1):293-296.
    [49] G.J.Qi,C.R.Zhang,H.F.Hu,et al.Three-dimensional silica fiber reinforced silicon nitride-based composites fabricated via different polysilazanes[J].Adv.Eng.Mater.2005,,7 (11):1043-1046.
    [50]刘坤.先驱体转化氮化硼及其复合材料的吸潮机理与防潮涂层研究[D].长沙:国防科技大学,2009.
    [51]李兴华.密度、浓度测量[M].北京:中国计量出版社,1991.
    [52]祝桂洪.陶瓷工艺实验[M].北京;中国建筑工业出版社,1987.
    [53]曹英斌.先驱体转化—热压工艺制备Cf/SiC复合材料工艺、结构、性能研究[D].长沙:国防科技大学,2001.
    [54] GB 6569-1986.工程陶瓷弯曲强度试验方法[S].1986.
    [55] GB/T 4339-1999.金属材料热膨胀特征参数的测定[S].1999.
    [56] R.S.Berry,S.A.Rice,J.Ross.Physical Chemistry[M],1980.
    [57]叶大伦,胡建华.使用无机物热力学数据手册[M].冶金工业出版社,2002.9.
    [58]傅献彩,沈文霞,姚天扬.物理化学[M].高等教育出版社,1982.4.
    [59]王树彬,邢建申,郑彧,张跃.石英纤维表面氮化硼涂层的制备及表征[J].稀有金属材料工程.2007.8(36):715-717.
    [60]张向宇.实用化学手册[M].国防工业出版社,1986.4.
    [61] G.W.Gokel.有机化学手册[M].化学工业出版社.2006.7.
    [62]郝元恺,肖加余,高性能复合材料学[M].北京:化学工业出版社,2004.
    [63] Y.J.Lee,H.J.Joo.Investigation on ablation behavior of CFRC composites prepared at different pressure[J].Composites Part A,2004,35:1285-1290.
    [64] G.J.Qi,C.R.Zhang,H.F.Hu,et al.Preparation of three-dimensional silica fiber reinforced silicon nitride composite using perhydropolysilazane as precursor[J].Mater.Lett,2005,59 (26):3256-3258.
    [65]陈帮.石英纤维的表面处理[D].长沙:国防科技大学,2007.
    [66]邢建申,王树彬,张跃.石英纤维析晶行为[J].复合材料学报,2006,23 (6):75-79.
    [67]杜耀惟.天线罩电信设计方法[M].北京:国防工业出版社,1993.
    [68] A.V.Goncharenko,V.Z.Lozovski,E.F.Venger.Lichtenecker’s equation:applicability and limitations[J].Opt.Commun,2000,174:19-32.
    [69] C.M.Regalado.A physical interpretation of logarithmic TDR calibration equations of volcanic soils and their solid fraction permittivity based on Lichtenecker’s mixing formulae[J].Geoderma,2004,123:41-50.
    [70]张玉娣.Cf/SiC复合材料反射镜坯体及过渡层的研究[D].长沙:国防科技大学,2005.

© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号

地址:北京市海淀区学院路29号 邮编:100083

电话:办公室:(+86 10)66554848;文献借阅、咨询服务、科技查新:66554700